The present invention relates to a method of and system for controlling a fluidic valve, and more particularly relates to a method of and system for controlling a fluidic vortex valve.
A conventional fluidic vortex valve is illustrated in FIGS. 1(a) and 1(b) of the accompanying drawings. The vortex valve has a housing 2 defining within it a cylindrical vortex chamber 4, the vortex chamber 4 being provided with two inlet ports 6, 8 and a centrally located outlet port 10. The central axis of the outlet port 10 is orthogonal to the central axes of the inlet ports 6, 8. The inlet port 6 and the outlet port 10 have a relatively large area compared to that of the inlet port 8.
When in use a supply fluid is injected radially into the vortex chamber 4 through the inlet port 6 and a control fluid is injected tangentially through the inlet port 8. If no fluid is injected into the inlet port 8 then substantially no tangential swirl is imparted to the supply fluid. The supply fluid flows through the vortex chamber 4 passing through a right angle to flow into the centrally located outlet port 10. There is little or no pressure gradient within the chamber 4 and the flow of fluid through the vortex valve is at its maximum level (FIG. 1(a)). If on the other hand the pressure of the control fluid exceeds the pressure of the supply fluid, the momentum of the interacting fluid streams generates a vortex within the chamber 4. The generation of the vortex gives rise to a radial pressure gradient within the chamber 4, the pressure gradient being dependent on, and increasing with, the pressure of the control fluid injected through the inlet port 8. If the pressure of the control fluid is increased relative to the pressure of the supply fluid beyond a predetermined limit the effect is to virtually arrest the flow of fluid through the inlet port 6. The fluid flow out of the vortex valve would in such a circumstance be equal to the flow of the control fluid entering the chamber 4 (FIG. 1(b)).
A known device for controlling the flow of the control fluid into the chamber 4 operates on electromagnetic principles. The device basically comprises a moving coil or moving iron mounted for rotation in response to an electrical signal received from a controller. A pin is mounted to pivot in response to rotation of the moving coil or iron, the pin being located adjacent to the inlet of a duct through which the control fluid is to be injected to the inlet port 8. The position of the pin relative to the inlet of the duct determines the pressure of the control fluid entering the chamber 4. The known device has been proposed for use in a method of and system for controlling vortex valves associated with thrusters used on missiles, the controller being the missile auto pilot. Such electromagnetically operable devices are in general not very robust and problems may arise from the high self induced stresses experienced when the devices are subjected to the extremely high gravitational forces created during the firing of a modern missile. Furthermore, the pin would have to operate in a high temperature highly corrosive gas environment, such as that found in the ducting associated with fluidic vortex valves used in guided missiles, In consequence, problems may arise in the manufacturing design of the pin or some alternative valve member which was used to control the tangential flow of hot gas emerging from the inlet port 8. In practice the valve member must be capable of accurately carrying out its function in the gas environment for a period at least equal to the expected flight duration of the missile.